Count those Ridges
Introduction
Ridge counting involves counting the ridges from the
core of a pattern to the delta(s).
* Arches have a ridge count of zero.
* For a loop, imagine a line from the delta to the core.
Count the # of ridges it crosses.
* For a whorl, count the # of ridges from each delta to the
core. The higher # is the ridge count.
A
B
C
Examples of some fingerprint patterns and the ridge count for each example. A: arch with
no tri-radius and ridge count of 0; B: loop with one tri-radius and a ridge count of 12; C:
whorl with two tri-radii and a ridge count of 15 (the higher of the two possible).
Purpose
A When the same pattern occurs on more than one finger does it have the
same ridge count?
B What is the class average ridge count # and what is the variation?
Hypothesis
Apparatus
index cards with prints
Procedure
1 Data was recorded in the chart below.
2 Class data was shared by entering into a common chart.
Safety
nil
Observations
Table 1. Personal Ridge Count Data:
Thumb
RIGHT HAND
Second
Third
Fourth
Fifth
Thumb
LEFT HAND
Second
Third
Fourth
Fifth
Pattern
Ridge Count
Total =
Pattern
Ridge Count
Total =
Pattern= Loop or Whorl
Total Ridge Count =
(right hand total + left hand total)
The TRC is the sum of ridge counts on all fingers of both hands.
Table 2.
You design a chart for class results.
Calculate average +/- Variation
Conclusion
Answer the purpose.
Discussion
1. Is the same ridge count produced when counting in either direction from the center to
the deltas of a whorl? Ie Do whorls have to be symmetrical?
2. Discuss the averages and variation among ridge counts. Are any patterns apparent?
(i.e. do loops have a significantly higher or lower average or variation, explain why
variation might be high or low, etc).